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Title: Metals exposure and risk of small-for-gestational age birth in a Canadian birth cohort: The MIREC study

Background: Lead, mercury, cadmium and arsenic are some of the most common toxic metals to which Canadians are exposed. The effect of exposure to current low levels of toxic metals on fetal growth restriction is unknown. Objective: The aim of this study was to examine relationships between exposure to lead, mercury, cadmium and arsenic during pregnancy, and risk of small for gestational age (SGA) birth. Methods: Lead, mercury, cadmium and arsenic levels were measured in blood samples from the first and third trimesters in 1835 pregnant women from across Canada. Arsenic species in first trimester urine were also assessed. Relative risks and 95% confidence intervals were estimated using log binomial multivariate regression. Important covariates including maternal age, parity, pre-pregnancy BMI, and smoking, were considered in the analysis. An exploratory analysis was performed to examine potential effect modification of these relationships by single nucleotide polymorphisms (SNPs) in GSTP1 and GSTO1 genes. Results: No association was found between blood lead, cadmium or arsenic and risk for SGA. We observed an increased risk for SGA for the highest compared to the lowest tertile of exposure for mercury (>1.6 µg/L, RR=1.56.; 95% CI=1.04–2.58) and arsenobetaine (>2.25 µg/L, RR=1.65; 95% CI=1.10–2.47) after adjustment for themore » effects of parity and smoking. A statistically significant interaction was observed in the relationship between dimethylarsinic acid (DMA) levels in urinary arsenic and SGA between strata of GSTO1 A104A (p for interaction=0.02). A marginally significant interaction was observed in the relationship between blood lead and SGA between strata of GSTP1 A114V (p for interaction=0.06). Conclusions: These results suggest a small increase in risk for SGA in infants born to women exposed to mercury and arsenic. Given the conflicting evidence in the literature this warrants further investigation in other pregnant populations. - Highlights: • Metals measured in blood or urine of pregnant women. • No association between blood lead, cadmium or arsenic and SGA. • Small increased risk for highest tertile of blood mercury. • Small increased risk for highest tertile of urinary arsenobetaine. • Further research needed to confirm observed associations.« less
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Department of Public Health Sciences, Queen’s University, Kingston, Ontario (Canada)
  2. Population Studies Division, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa (Canada)
  3. Sainte Justine University Hospital Research Center, University of Montreal, Montreal (Canada)
  4. Center for Perinatal, Pediatric & Environmental Epidemiology, Yale School of Public Health, New Haven, CT (United States)
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Research; Journal Volume: 140; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States